Water filter materials, water filters and kits containing silver coated particles and processes for using the same

ABSTRACT

A filter for providing potable water is provided. The filter includes a housing having an inlet and an outlet, a filter material disposed within the housing, the filter material formed at least in part from a plurality of mesoporous, basic, and reduced-oxygen activated carbon filter particles. Preferably, at least some of the mesoporous activated carbon filter particles are coated with silver or a silver containing material. Kits comprising filters and information relating to the killing or removal of bacteria, viruses, and microbials are also provided.

CROSS REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 120, this application is a continuation-in-partof U.S. application Ser. Nos. 10/464,209 now abandoned and 10/464,210,both of which were filed on Jun. 18, 2003 which arecontinuations-in-part of U.S. application Ser. Nos. 09/935,962 and09/935,810, both of which were filed on Aug. 23, 2001 now abandoned, thesubstances of which are incorporated herein by reference. Additionally,pursuant to 35 U.S.C. § 120, this application is a continuation ofInternational Application No. PCT/US03/05416 designating the U.S., filedFeb. 21, 2003, and is also a continuation of International ApplicationNo. PCT/US03/05409 designating the U.S., filed Feb. 21, 2003, thesubstances of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of water filter materials andwater filters and processes for using the same, and, more particularly,to the field of water filters containing mesoporous activated carbonparticles.

BACKGROUND OF THE INVENTION

Water may contain many different kinds of contaminants including, forexample, particulates, harmful chemicals, and microbiological organisms,such as bacteria, parasites, protozoa and viruses. In a variety ofcircumstances, these contaminants must be removed before the water canbe used. For example, in many medical applications and in themanufacture of certain electronic components, extremely pure water isrequired. As a more common example, any harmful contaminants must beremoved from the water before it is potable, i.e., fit to consume.Despite modem water purification means, the general population is atrisk, and in particular infants and persons with compromised immunesystems are at considerable risk.

In the U.S. and other developed countries, municipally treated watertypically includes one or more of the following impurities: suspendedsolids, bacteria, parasites, viruses, organic matter, heavy metals, andchlorine. Breakdown and other problems with water treatment systemssometimes lead to incomplete removal of bacteria and viruses. In othercountries, there are deadly consequences associated with exposure tocontaminated water, as some of them have increasing populationdensities, increasingly scarce water resources, and no water treatmentutilities. It is common for sources of drinking water to be in closeproximity to human and animal waste, such that microbiologicalcontamination is a major health concern. As a result of waterbornemicrobiological contamination, an estimated six million people die eachyear, half of which are children under 5 years of age.

In 1987, the U.S. Environmental Protection Agency (EPA) introduced the“Guide Standard and Protocol for Testing Microbiological WaterPurifiers”. The protocol establishes minimum requirements regarding theperformance of drinking water treatment systems that are designed toreduce specific health related contaminants in public or private watersupplies. The requirements are that the effluent from a water supplysource exhibits 99.99% (or equivalently, 4 log) removal of viruses and99.9999% (or equivalently, 6 log) removal of bacteria against achallenge. Under the EPA protocol, in the case of viruses, the influentconcentration should be 1×10⁷ viruses per liter, and in the case ofbacteria, the influent concentration should be 1×10⁸ bacteria per liter.Because of the prevalence of Escherichia coli (E. coli, bacterium) inwater supplies, and the risks associated with its consumption, thismicroorganism is used as the bacterium in the majority of studies.Similarly, the MS-2 bacteriophage (or simply, MS-2 phage) is typicallyused as the representative microorganism for virus removal because itssize and shape (i.e., about 26 nm and icosahedral) are similar to manyviruses. Thus, a filter's ability to remove MS-2 bacteriophagedemonstrates its ability to remove other viruses.

Due to these requirements and a general interest in improving thequality of potable water, there is a continuing desire to provideprocesses for manufacturing filter materials and filters, which arecapable of removing bacteria and/or viruses from a fluid.

SUMMARY OF THE INVENTION

A filter for providing potable water is provided. The filter includes ahousing having an inlet and an outlet, a filter material disposed withinthe housing, the filter material formed at least in part from aplurality of mesoporous activated carbon filter particles. The filtermaterial preferably comprises particles selected from the groupconsisting of mesoporous activated carbon filter particles coatedentirely with silver or a silver containing material, mesoporousactivated carbon filter particles partially coated with silver or asilver containing material, silver particles and mixtures thereof.

In another aspect of the present invention there is provided a kitcomprising a filter for providing potable water. The filter comprises ahousing having an inlet and an outlet, and a filter material disposedwithin the housing formed at least in part from a plurality ofmesoporous activated carbon filter particles. The kit further comprisesa package for containing the filter and either the package or the filterhousing comprises information that the filter or filter materialprovides: bacterial removal; virus removal; microbial removal; killingof bacteria, killing of viruses, killing of microbials, or anycombination of these.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed that the presentinvention will be better understood from the following description takenin conjunction with the accompanying drawings in which:

FIG. 1 a is a BET nitrogen adsorption isotherm of mesoporous and acidicactivated carbon particles CA-10, and mesoporous, basic, andreduced-oxygen activated carbon particles TA4-CA-10.

FIG. 1 b is a BET nitrogen adsorption isotherm of mesoporous and basicactivated carbon particles RGC, and mesoporous, basic, andreduced-oxygen activated carbon THe4-RGC.

FIG. 2 a is a mesopore volume distribution of the particles of FIG. 1 a.

FIG. 2 b is a mesopore volume distribution of the particles of FIG. 1 b.

FIG. 3 a is a point-of-zero-charge graph of the particles of FIG. 1 a.

FIG. 3 b is a point-of-zero-charge graph of the particles of FIG. 1 b.

FIG. 4 is a cross sectional side view of an axial flow filter made inaccordance with the present invention.

FIG. 5 a illustrates the E. coli bath concentration as a function oftime for the activated carbon particles of FIG. 1 a.

FIG. 5 b illustrates the E. coli bath concentration as a function oftime for activated carbon particles of FIG. 1 b.

FIG. 6 a illustrates the MS-2 bath concentration as a function of timefor the activated carbon particles of FIG. 1 a.

FIG. 6 b illustrates the MS-2 bath concentration as a function of timefor the activated carbon particles of FIG. 1 b.

FIG. 7 a illustrates the E. coli flow concentration as a function of thecumulative volume of water through 2 filters; one containing RGCmesoporous and basic activated carbon, and the other containing coconutmicroporous activated carbon particles.

FIG. 7 b illustrates the MS-2 flow concentration as a function of thecumulative volume of water through of 2 filters; one containing RGCmesoporous and basic activated carbon, and the other containing coconutmicroporous activated carbon particles.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

All documents cited are, in relevant part, incorporated herein byreference. The citation of any document is not to be construed as anadmission that it is prior art with respect to the present invention.

I. Definitions

As used herein, the terms “filters” and “filtration” refer to structuresand mechanisms, respectively, associated with microorganism removal(and/or other contaminant removal), via primarily adsorption and/or sizeexclusion to a lesser extent.

As used herein, the phrase “filter material” is intended to refer to anaggregate of filter particles. The aggregate of the filter particlesforming a filter material can be either homogeneous or heterogeneous.The filter particles can be uniformly or non-uniformly distributed(e.g., layers of different filter particles) within the filter material.The filter particles forming a filter material also need not beidentical in shape or size and may be provided in either a loose orinterconnected form. For example, a filter material might comprisemesoporous and basic activated carbon particles in combination withactivated carbon fibers, and these filter particles may be eitherprovided in loose association or partially or wholly bonded by apolymeric binder or other means to form an integral structure.

As used herein, the phrase “filter particle” is intended to refer to anindividual member or piece, which is used to form at least part of afilter material. For example, a fiber, a granule, a bead, etc. are eachconsidered filter particles herein. Further, the filter particles canvary in size, from impalpable filter particles (e.g., a very finepowder) to palpable filter particles.

As used herein, the phrase “filter material pore volume” refers to thetotal volume of the inter-particle pores in the filter material withsizes larger than 0.1 μm.

As used herein, the phrase “filter material total volume” refers to thesum of the inter-particle pore volume and the volume occupied by thefilter particles.

As used herein, the terms “microorganism”, “microbiological organism”and “pathogen” are used interchangeably. These terms refer to varioustypes of microorganisms that can be characterized as bacteria, viruses,parasites, protozoa, and germs.

As used herein, the phrase “Bacteria Removal Index” (BRI) of filterparticles is defined as:BRI=100×[1−(bath concentration of E. coli bacteria atequilibrium/control concentration of E. coli bacteria)],wherein “bath concentration of E. coli bacteria at equilibrium” refersto the concentration of bacteria at equilibrium in a bath that containsa mass of filter particles having a total external surface area of 1400cm² and Sauter mean diameter less than 55 μm, as discussed more fullyhereafter. Equilibrium is reached when the E. coli concentration, asmeasured at two time points 2 hours apart, remains unchanged to withinhalf order of magnitude. The phrase “control concentration of E. colibacteria” refers to the concentration of E. coli bacteria in the controlbath, and is equal to about 3.7×10⁹ CFU/L. The Sauter mean diameter isthe diameter of a particle whose surface-to-volume ratio is equal tothat of the entire particle distribution. Note that the term “CFU/L”denotes “colony-forming units per liter”, which is a typical term usedin E. coli counting. The BRI index is measured without application ofchemical agents that provide bactericidal effects. An equivalent way toreport the removal capability of filter particles is with the “BacteriaLog Removal Index” (BLRI), which is defined as:BLRI=−log[1−(BRI/100)].

The BLRI has units of “log” (where “log” stands for logarithm). Forexample, filter particles that have a BRI equal to 99.99% have a BLRIequal to 4 log. A test procedure for determining BRI and BLRI values isprovided hereafter.

As used herein, the phrase “Virus Removal Index” (VRI) for filterparticles is defined as:VRI=100×[1−(bath concentration of MS-2 phages at equilibrium/controlconcentration of MS-2 phages)],wherein “bath concentration of MS-2 phages at equilibrium” refers to theconcentration of phages at equilibrium in a bath that contains a mass offilter particles having a total external surface area of 1400 cm² andSauter mean diameter less than 55 μm, as discussed more fully hereafter.Equilibrium is reached when the MS-2 concentration, as measured at twotime points 2 hours apart, remains unchanged to within half order ofmagnitude. The phrase “control concentration of MS-2 phages” refers tothe concentration of MS-2 phages in the control bath, and is equal toabout 6.7×10⁷ PFU/L. Note that the term “PFU/L” denotes “plaque-formingunits per liter”, which is a typical term used in MS-2 counting. The VRIindex is measured without application of chemical agents that providevirucidal effects. An equivalent way to report the removal capability offilter particles is with the “Viruses Log Removal Index” (VLRI), whichis defined as:VLRI=−log [1−(VRI/100)].

The VLRI has units of “log” (where “log” is the logarithm). For example,filter particles that have a VRI equal to 99.9% have a VLRI equal to 3log. A test procedure for determining VRI and VLRI values is providedhereafter.

As used herein, the phrase “Filter Bacteria Log Removal (F-BLR)” refersto the bacteria removal capability of the filter after the flow of thefirst 2,000 filter material pore volumes. The F-BLR is defined andcalculated as:F-BLR=−log [(effluent concentration of E. coli)/(influent concentrationof E. coli)],where the “influent concentration of E. coli” is set to about 1×10⁸CFU/L continuously throughout the test and the “effluent concentrationof E. coli” is measured after about 2,000 filter material pore volumesflow through the filter. F-BLR has units of “log” (where “log” is thelogarithm). Note that if the effluent concentration is below the limitof detection of the technique used to assay, then the effluentconcentration for the calculation of the F-BLR is considered to be thelimit of detection. Also, note that the F-BLR is measured withoutapplication of chemical agents that provide bactericidal effects.

As used herein, the phrase “Filter Viruses Log Removal (F-VLR)” refersto the virus removal capability of the filter after the flow of thefirst 2,000 filter material pore volumes. The F-VLR is defined andcalculated as:F-VLR=−log [(effluent concentration of MS-2)/(influent concentration ofMS-2)],where the “influent concentration of MS-2” is set to about 1×10⁷ PFU/Lcontinuously throughout the test and the “effluent concentration ofMS-2” is measured after about 2,000 filter material pore volumes flowthrough the filter. F-VLR has units of “log” (where “log” is thelogarithm). Note that if the effluent concentration is below the limitof detection of the technique used to assay, then the effluentconcentration for the calculation of the F-VLR is considered to be thelimit of detection. Also, note that the F-VLR is measured withoutapplication of chemical agents that provide virucidal effects.

As used herein, the phrase “total external surface area” is intended torefer to the total geometric external surface area of one or more of thefilter particles, as discussed more fully hereafter.

As used herein, the phrase “specific external surface area” is intendedto refer to the total external surface area per unit mass of the filterparticles, as discussed more fully hereafter.

As used herein, the term “micropore” is intended to refer to anintra-particle pore having a width or diameter less than 2 nm (orequivalently, 20 Å).

As used herein, the term “mesopore” is intended to refer to anintra-particle pore having a width or diameter between 2 nm and 50 nm(or equivalently, between 20 Å and 500 Å).

As used herein, the term “macropore” is intended to refer to anintra-particle pore having a width or diameter greater than 50 nm (orequivalently, 500 Å)

As used herein, the phrase “total pore volume” and its derivatives areintended to refer to the volume of all the intra-particle pores, i.e.,micropores, mesopores and macropores. The total pore volume iscalculated as the volume of nitrogen adsorbed at a relative pressure of0.9814 using the BET process (ASTM D 4820-99 standard), a process wellknown in the art.

As used herein, the phrase “micropore volume” and its derivatives areintended to refer to the volume of all micropores. The micropore volumeis calculated from the volume of nitrogen adsorbed at a relativepressure of 0.15 using the BET process (ASTM D 4820-99 standard), aprocess well known in the art.

As used herein, the phrase “sum of the mesopore and macropore volumes”and its derivatives are intended to refer to the volume of all mesoporesand macropores. The sum of the mesopore and macropore volumes is equalto the difference between the total pore volume and micropore volume, orequivalently, is calculated from the difference between the volumes ofnitrogen adsorbed at relative pressures of 0.9814 and 0.15 using the BETprocess (ASTM D 4820-99 standard), a process well known in the art.

As used herein, the phrase “pore size distribution in the mesoporerange” is intended to refer to the distribution of the pore size ascalculated by the Barrett, Joyner, and Halenda (BJH) process, a processwell known in the art.

As used herein, the term “carbonization” and its derivatives areintended to refer to a process in which the non-carbon atoms in acarbonaceous substance are reduced.

As used herein, the term “activation” and its derivatives are intendedto refer to a process in which a carbonized substance is rendered moreporous.

As used herein, the term “activated carbon particles” or “activatedcarbon filter particles” and their derivatives are intended to refer tocarbon particles that have been subjected to an activation process.

As used herein, the phrase “point of zero charge” is intended to referto the pH above which the total surface of the carbon particles isnegatively charged. A well known test procedure for determining thepoint of zero charge is set forth hereafter.

As used herein, the term “basic” is intended to refer to filterparticles with a point of zero charge greater than 7.

As used herein, the term “acidic” is intended to refer to filterparticles with a point of zero charge less than 7.

As used herein, the phrase “mesoporous activated carbon filter particle”refers to an activated carbon filter particle wherein the sum of themesopore and macropore volumes may be greater than 0.12 mL/g.

As used herein, the phrase “microporous activated carbon filterparticle” refers to an activated carbon filter particle wherein the sumof the mesopore and macropore volumes may be less than 0.12 mL/g.

As used herein, the phrase “mesoporous and basic activated carbon filterparticle” is intended to refer to an activated carbon filter particlewherein the sum of the mesopore and macropore volumes may be greaterthan 0.12 mL/g and has a point of zero charge greater than 7.

As used herein, the phrase “mesoporous, basic, and reduced-oxygenactivated carbon filter particle” is intended to refer to an activatedcarbon filter particle wherein the sum of the mesopore and macroporevolumes may be greater than 0.12 mL/g, has a point of zero chargegreater than 7, and has a bulk oxygen percentage by weight of 1.5% orless.

As used herein, the phrase “mesoporous and acidic activated carbonfilter particle” is intended to refer to an activated carbon filterparticle wherein the sum of the mesopore and macropore volumes may begreater than 0.12 mL/g and has a point of zero charge less than 7.

As used herein, the phrase “starting material” refers to any precursorcontaining mesopores and macropores or capable of yielding mesopores andmacropores during carbonization and/or activation.

As used herein, the phrase “axial flow” refers to flow through a planarsurface and perpendicularly to that surface.

As used herein, the phrase “radial flow” typically refers to flowthrough essentially cylindrical or essentially conical surfaces andperpendicularly to those surfaces.

As used herein, the phrase “face area” refers to the area of the filtermaterial initially exposed to the influent water. For example, in thecase of axial flow filters, the face area is the cross sectional area ofthe filter material at the entrance of the fluid, and in the case of theradial flow filter, the face area is the outside area of the filtermaterial.

As used herein, the phrase “filter depth” refers to the linear distancethat the influent water travels from the entrance to the exit of thefilter material. For example, in the case of axial flow filters, thefilter depth is the thickness of the filter material, and in the case ofthe radial flow filter, the filter depth is half of the differencebetween the outside and inside diameters of the filter material.

As used herein, the phrases “average fluid residence time” and/or“average fluid contact time” refer to the average time that the fluid isin contact with the-filter particles inside the filter as it travelsthrough the filter material, and are calculated as the ratio of thefilter material pore volume to the fluid flow rate.

As used herein, the phrases “filter porosity” and/or “filter bedporosity” refer to the ratio of the filter material pore volume to thefilter material total volume.

As used herein, the phrase “inlet” refers to the means in which a fluidis able to enter the filter or filter material. For example, the inletcan be a structure that is part of the filter, or the filter materialface area.

As used herein, an “outlet” refers to the means in which a fluid is ableto exit the filter or filter material. For example, the outlet can be astructure that is part of the filter, or the cross sectional area of thefilter material at the exit of the fluid.

II. Mesoporous Activated Carbon Filter Particles

Unexpectedly it has been found that mesoporous activated carbon filterparticles adsorb a larger number of microorganisms compared toInicroporous activated carbon filter particles. Also, unexpectedly ithas been found that mesoporous and basic activated carbon filterparticles adsorb a larger number of microorganisms compared to thatadsorbed by mesoporous and acidic activated carbon filter particles.Furthermore, it has been found unexpectedly that mesoporous, basic, andreduced-oxygen activated carbon filter particles adsorb a larger numberof microorganisms compared to that adsorbed by mesoporous and basicactivated carbon filter particles without reduced bulk oxygen percentageby weight.

Although not wishing to be bound by any theory applicants hypothesizethat, with regard to porosity, a large number of mesopores and/ormacropores provides more convenient adsorption sites (openings orentrances of the mesopores/macropores) for the pathogens, theirfimbriae, and surface polymers (e.g. proteins, lipopolysaccharides,oligosaccharides and polysaccharides) that constitute the outermembranes, capsids and envelopes of the pathogens because the typicalsize of such is similar to that of the entrances of the mesopores andmacropores. Also, mesoporosity and macroporosity may correlate with oneor more surface properties of the carbon, such as surface roughness.

Also, not wishing to be bound by theory, applicants hypothesize thatbasic activated carbon surfaces contain the types of functionality thatare necessary to attract a larger number of microorganisms compared tothose attracted by an acidic carbon surface. This enhanced adsorptiononto the basic carbon surfaces might be attributed to the fact that thebasic carbon surfaces attract the typically negatively-chargedmicroorganisms and functional groups on their surface. Applicantsfurther hypothesize that basic carbon is capable of producingdisinfectants when placed in water by reducing molecular oxygen.Although the final product of the reduction is hydroxide, applicantsbelieve that reactive oxygen intermediates, such as superoxide,hydroperoxide, and/or hydroxy radicals, are formed and maybesufficiently long-lived to diffuse from carbon into bulk solution.

Furthermore, applicants believe that carbon becomes more basic as thebulk oxygen percentage by weight is reduced. A low bulk oxygenpercentage by weight may lead to improved bacteria/viruses adsorptionbecause there will be: (1) less carboxylic acids and hence a lessnegative surface to repel bacteria/viruses; and (2) a less hydratedsurface so that water is more easily displaced by bacteria/viruses asthey attempt to adsorb to the surface (i.e., less of an energy penaltyfor the bacteria/virus to displace other species already occupying siteson the surface). This latter reason (i.e., a less hydrated surface) alsoties in with the idea that the ideal surface, discussed hereafter,should be somewhat hydrophobic (that is, it should have just enoughoxygen substitution on the edge carbon atoms to allow it to wet out, butnot so much as to make it excessively hydrophilic).

The filter particles can be provided in a variety of shapes and sizes.For example, the filter particles can be provided in simple forms suchas powder, granules, fibers, and beads. The filter particles can beprovided in the shape of a sphere, polyhedron, cylinder, as well asother symmetrical, asymmetrical, and irregular shapes. Further, thefilter particles can also be formed into complex forms such as webs,screens, meshes, non-wovens, wovens, and bonded blocks, which may or maynot be formed from the simple forms described above. Like shape, thesize of the filter particle can also vary, and the size need not beuniform among filter particles used in any single filter. In fact, itcan be desirable to provide filter particles having different sizes in asingle filter. Generally, the size of the filter particles may bebetween about 0.1 μm and about 10 mm, preferably between about 0.2 μmand about 5 mm, more preferably between about 0.4 μm and about 1 mm, andmost preferably between about 1 μm and about 500 μm. For spherical andcylindrical particles (e.g., fibers, beads, etc.), the above-describeddimensions refer to the diameter of the filter particles. For filterparticles having substantially different shapes, the above-describeddimensions refer to the largest dimension (e.g. length, width, orheight).

The filter particles may be the product of any precursor that containsmesopores and macropores or generates mesopores and macropores duringcarbonization and/or activation. For example, and not by way oflimitation, the filter particles can be wood-based activated carbonparticles, coal-based activated carbon particles, peat-based activatedcarbon particles, pitch-based activated carbon particles, tar-basedactivated carbon particles, bean-based activated carbon particles, otherlignocellulosic-based activated carbon particles, and mixtures thereof.

Activated carbon can display acidic, neutral, or basic properties. Theacidic properties are associated with oxygen-containing functionalitiesor functional groups, such as, and not by way of limitation, phenols,carboxyls, lactones, hydroquinones, anhydrides, and ketones. The basicproperties have heretofore been associated with functionalities such aspyrones, chromenes, ethers, carbonyls, as well as the basal plane πelectrons. The acidity or basicity of the activated carbon particles isdetermined with the “point of zero charge” technique (Newcombe, G., etal., Colloids and Surfaces A: Physicochemical and Engineering Aspects,78, 65-71 (1993)), the substance of which is incorporated herein byreference. The technique is further described in Section VII hereafter.Filter particles of the present invention may have a point of zerocharge between 1 and 14, preferably greater than about 4, preferablygreater than about 6, preferably greater than about 7, preferablygreater than about 8, more preferably greater than about 9, and mostpreferably between about 9 and about 12.

The point of zero charge of activated carbons inversely correlates withtheir bulk oxygen percentage by weight. Filter particles of the presentinvention may have a bulk oxygen percentage by weight less than about5%, preferably less than about 2.5%, preferably less than about 2.3%,preferably less than about 2%, more preferably less than about 1.2%, andmost preferably less than about 1%, and/or greater than about 0.1%,preferably greater than about 0.2%, more preferably greater than about0.25%, and most preferably greater than about 0.3%. Also, the point ofzero charge of activated carbon particles correlates with the ORP of thewater containing the particles because the point of zero charge is ameasure of the ability of the carbon to reduce oxygen (at least forbasic carbons). Filter particles of the present invention may have anORP less than about 570 mV, preferably less than about 465 mV,preferably less than about 400, preferably less than about 360 mV,preferably less than about 325 mV, and most preferably between about 290mV and about 175 mV.

The electric resistance of the activated carbon filter particles orfilter material is one of their important properties as it relates totheir ability to form a filter block. For example, a resistive heatingmethod can be used to form filter blocks, wherein a filter material isheated by passing electricity between 2 ends of the filter material. Theelectric resistance of the filter material will control its ability toheat in a short time. The electric resistance is measured by formingfilter blocks using conditions as those mentioned in Examples 3 and 4,supra, and measuring the electric resistance between the 2 faces of theblock by contacting them with 2 electrodes from a voltmeter. Exemplaryelectric resistances of the filters of Examples 3 and 4 are about 350Ωand about 40Ω, respectively. Also, the respective electric resistancesof filters made with CARBOCHEM CA-10 of Example 1, supra, and TA4-CA10of Example 2, supra, are about 1.3 MΩ, and about 100Ω.

Filter particles may be achieved by way of treating a starting materialas described herebelow. The treatment conditions may include atmospherecomposition, pressure, temperature, and/or time. The atmospheres of thepresent invention may be reducing or inert. Heating the filter particlesin the presence of reducing atmospheres, steam, or inert atmospheresyields filter material with reduced surface oxygen functionality.Examples of suitable reducing atmospheres may include hydrogen,nitrogen, dissociated ammonia, carbon monoxide, and/or mixtures.Examples of suitable inert atmospheres may include argon, helium, and/ormixtures thereof.

The treatment temperature, when the activated carbon particles do notcontain any noble metal catalysts (e.g., platinum, gold, palladium) maybe between about 600° C. and about 1,200° C., preferably between about700° C. and about 1,100° C., more preferably between about 800° C. andabout 1,050° C., and most preferably between about 900° C. and about1,000° C. If the activated carbon particles contain noble metalcatalysts, the treatment temperature may be between about 100° C. andabout 800° C., preferably between about 200° C. and about 700° C., morepreferably between about 300° C. and about 600° C., and most preferablybetween about 350° C. and about 550° C.

The treatment time may be between about 2 minutes and about 10 hours,preferably between about 5 minutes and about 8 hours, more preferablybetween about 10 minutes and about 7 hours, and most preferably betweenabout 20 minutes and about 6 hours. The gas flow rate may be betweenabout 0.25 standard L/h.g (i.e., standard liters per hour and gram ofcarbon; 0.009 standard ft³/h.g) and about 60 standard L/h.g (2.1standard ft³/h.g), preferably between about 0.5 standard L/h.g (0.018standard ft³/h.g) and about 30 standard L/h.g (1.06 standard ft³/h.g),more preferably between about 1.0 standard L/h.g (0.035 standardft³/h.g) and about 20 standard L/h.g (0.7 standard ft³/h.g), and mostpreferably between about 5 standard L/h.g (0.18 standard ft³/h.g) andabout 10 standard L/h.g (0.35 standard ft³/h.g). The pressure can bemaintained greater than, equal to, or less than atmospheric during thetreatment time. As will be appreciated, other processes for producing amesoporous, basic, and reduced-oxygen activated carbon filter materialcan be employed. Also, such treatment of a starting material asdescribed above may be repeated multiple times, depending on thestarting material, in order to obtain a filter material.

A starting material may be commercially obtained, or may be made by themethods which are well known in the art, as described in, for example,Jagtoyen, M., and F. Derbyshire, Carbon, 36(7-8), 1085-1097 (1998), andEvans, et al., Carbon, 37, 269-274 (1999), and Ryoo et al., J. Phys.Chem. B, 103(37), 7743-7746 (1999), the substances of which are hereinincorporated by reference. Typical chemicals used foractivation/carbonization include phosphoric acid, zinc chloride,ammonium phosphate, etc., which may be used in combination with themethods described in the two immediately cited journals.

The Brunauer, Emmett and Teller (BET) specific surface area and theBarrett, Joyner, and Halenda (BJH) pore size distribution can be used tocharacterize the pore structure of particles. Preferably, the BETspecific surface area of the filter particles may be between about 500m²/g and about 3,000 m²/g, preferably between about 600 m²/g to about2,800 m²/g, more preferably between about 800 m²/g and about 2,500 m²/g,and most preferably between about 1,000 m²/g and about 2,000 m²/g.Referring to FIG. 1 a, typical nitrogen adsorption isotherms, using theBET process, of a mesoporous, basic, and reduced-oxygen wood-basedactivated carbon (TA4-CA-10), and a mesoporous and acidic wood-basedactivated carbon (CA-10) are illustrated. Referring to FIG. 1 b, typicalnitrogen adsorption isotherms, using the BET process, of a mesoporousand basic wood-based activated carbon (RGC), and a mesoporous, basic,and reduced-oxygen wood-based activated carbon (THe4-RGC) areillustrated.

The total pore volume of the mesoporous and basic activated carbonparticles is measured during the BET nitrogen adsorption and iscalculated as the volume of nitrogen adsorbed at a relative pressure,P/P₀, of 0.9814. More specifically and as is well known in the art, thetotal pore volume is calculated by multiplying the “volume of nitrogenadsorbed in mL(STP)/g” at a relative pressure of 0.9814 with theconversion factor 0.00156, that converts the volume of nitrogen at STP(standard temperature and pressure) to liquid. The total pore volume ofthe filter particles may be greater than about 0.4 ML/g, or greater thanabout 0.7 mL/g, or greater than about 1.3 mL/g, or greater than about 2mL/g, and/or less than about 3 mL/g, or less than about 2.6 mL/g, orless than about 2 mL/g, or less than about 1.5 mL/g.

The sum of the mesopore and macropore volumes is measured during the BETnitrogen adsorption and calculated as the difference between the totalpore volume and the volume of nitrogen adsorbed at P/P₀ of 0.15. The sumof the mesopore and macropore-volumes of the filter particles may begreater than about 0.12 mL/g, or greater than about 0.2 mL/g, or greaterthan about 0.4 mL/g, or greater than about 0.6 mL/g, or greater thanabout 0.75 mL/g, and/or less than about 2.2 mL/g, or less than about 2mL/g, or less than about 1.5 mL/g, or less than about 1.2 mL/g, or lessthan about 1 mL/g.

The BJH pore size distribution can be measured using the Barrett,Joyner, and Halenda (BJH) process, which is described in J. Amer. Chem.Soc., 73, 373-80 (1951) and Gregg and Sing, ADSORPTION, SURFACE AREA,AND POROSITY, 2nd edition, Academic Press, New York (1982), thesubstances of which are incorporated herein by reference. In oneembodiment, the pore volume may be at least about 0.01 mL/g for any porediameter between about 4 nm and about 6 nm. In an alternate embodiment,the pore volume may be between about 0.01 mL/g and about 0.04 mL/g forany pore diameter between about 4 nm and about 6 nm. In yet anotherembodiment, the pore volume may be at least about 0.03 mL/g for porediameters between about 4 nm and about 6 nm or is between about 0.03mL/g and about 0.06 mL/g. In a preferred embodiment, the pore volume maybe between about 0.015 mL/g and about 0.06 mL/g for pore diametersbetween about 4 nm and about 6 nm. FIG. 2 a illustrates typical mesoporevolume distributions, as calculated by the BJH process, of a mesoporous,basic, and reduced-oxygen activated carbon (TA4-CA-10), and a mesoporousand acidic wood-based activated carbon (CA-10). FIG. 2 b illustratestypical mesopore volume distributions, as calculated by the BJH process,of a mesoporous and basic wood-based activated carbon (RGC), and amesoporous, basic, and reduced-oxygen wood-based activated carbon(THe4-RGC).

The ratio of the sum of the mesopore and macropore volumes to the totalpore volume may be greater than about 0.3, preferably greater than about0.4, preferably greater than about 0.6, and most preferably betweenabout 0.7 and about 1.

The total external surface area is calculated by multiplying thespecific external surface area by the mass of the filter particles, andis based on the dimensions of the filter particles. For example, thespecific external surface area of mono-dispersed (i.e., with uniformdiameter) fibers is calculated as the ratio of the area of the fibers(neglecting the 2 cross sectional areas at the ends of the fibers) tothe weight of the fibers. Thus, the specific external surface area ofthe fibers is equal to: 4/ Dρ, where D is the fiber diameter and ρ isthe fiber density. For monodispersed spherical particles, similarcalculations yield the specific external surface area as equal to: 6/Dρ, where D is the particle diameter and ρ is the particle density. Forpoly-dispersed fibers, spherical or irregular particles, the specificexternal surface area is calculated using the same respective formulaeas above after substituting D _(3,2) for D, where D _(3,2) is the Sautermean diameter, which is the diameter of a particle whosesurface-to-volume ratio is equal to that of the entire particledistribution. A process, well known in the art, to measure the Sautermean diameter is by laser diffraction, for example using the Malvernequipment (Malvern Instruments Ltd., Malvern, U.K.). The specificexternal surface area of the filter particles may be between about 10cm²/g and about 100,000 cm²/g, preferably between about 50 cm²/g andabout 50,000 cm²/g, more preferably between about 100 cm²/g and about10,000 cm²/g, and most preferably between about 500 cm²/g and about7,000 cm²/g.

The BRI of the mesoporous, or mesoporous and basic, or mesoporous, basicand reduced-oxygen activated carbon particles, when measured accordingto the test procedure set forth herein, may be greater than about 99%,preferably greater than about 99.9%, more preferably greater than about99.99%, and most preferably greater than about 99.999%. Equivalently,the BLRI of the mesoporous, or mesoporous and basic, or mesoporous,basic and reduced-oxygen activated carbon particles may be greater thanabout 2 log, preferably greater than about 3 log, more preferablygreater than about 4 log, and most preferably greater than about 5 log.The VRI of the mesoporous, or mesoporous and basic, or mesoporous, basicand reduced-oxygen activated carbon particles, when measured accordingto the test procedure set forth herein, may be greater than about 90%,preferably greater than about 95%, more preferably greater than about99%, and most preferably greater than about 99.9%. Equivalently, theVLRI of the mesoporous, or mesoporous and basic, or mesoporous, basicand reduced-oxygen activated carbon particles may be greater than about1 log, preferably greater than about 1.3 log, more preferably greaterthan about 2 log, and most preferably greater than about 3 log.

The steady state, one-dimensional, “clean” bed filtration theory(assuming negligible dispersive transport and desorption ofmicroorganisms) for an axial flow filter (Yao et al., Environ. Sci.Technol. 5, 1102-1112 (1971)), the substance of which is incorporatedherein by reference, describes that:C/C ₀=exp(−λL),  (1)where C is the effluent concentration, C₀ is the influent concentration,λ is the filter coefficient with units of reciprocal length, and L isthe depth of the filter. Note that based on the definitions above, thenumber of collisions that a non-attaching microorganism will experienceas it travels over a distance L through the filter will be (λ/α)L, whereα is the “clean” bed sticking coefficient (also called, collisionefficiency), defined as the ratio of the number of microorganisms thatstick to the collector surface to the number of microorganisms thatstrike the collector surface. Equation 1 is also valid for radial flowfilters if L is substituted by R₀−R_(i), where R₀ is the outside radiusand R_(i) is the inside radius, and the filter coefficient is averagedover the thickness of the filter. The filter coefficient for aparticle-containing bed (not fibers) is as follows:λ=(3(1−ε)ηα)/2d _(c),  (2)where ε is the filter bed porosity, η is the single-collectorefficiency, defined as the ratio of the number of microorganisms thatstrike the collector surface to the number of microorganisms that flowtowards the collector surface, and d_(c) is the collector particlediameter. The factor (3/2) in the formula above is valid for sphericalor spherical-like particles. For cylindrical particles (e.g. fibers) theterm becomes (4/ π), and d_(c) is then the diameter of the cylinder.Also, note that the term “clean” bed means that the collector surfaceshave not yet accumulated enough microorganisms to cause a reduction inthe deposition efficiency of the new microorganisms (i.e., blocking).

Based on the above “clean” bed filtration model, the F-BLR and F-VLR canbe calculated as follows:F-BLR or F-VLR=−log(C/C ₀)=(λL/2.3).  (3)

The single-collector efficiency, η, is calculated using the Rajagopalanand Tien model (RT model; AIChE J., 22(3), 523-533 (1976), and AlChE J.,28, 871-872 (1982)) as follows:η=4A _(s) ^(1/3) Pe ^(−2/3) +A _(s) Lo ^(1/8) R ^(15/8)+0.00338A _(s) G^(6/5) R ^(−2/5),  (4)where

${A_{s} = \frac{2\left( {1 - \gamma^{5}} \right)}{2 - {3\gamma} + {3\gamma^{5}} - {2\gamma^{6}}}},{\gamma = \left( {1 - ɛ} \right)^{\frac{1}{3}}},$Pe is the dimensionless Peclet number

${{Pe} = \frac{3\mu\;\pi\; U\; d_{c}d_{m}}{kT}},$Lo is the dimensionless London—van der Waals number

${{Lo} = \frac{4H}{9\pi\;\mu\; d_{m}^{2}U}},$R is the dimensionless interception number

${R = \frac{d_{m}}{d_{c}}},$G is the dimensionless sedimentation number

${G = \frac{{g\left( {\rho_{m} - \rho_{f}} \right)}d_{m}^{2}}{18\;\mu\; U}},$μ is the dynamic fluid viscosity (equal to 1 mPa·s for water), U is thesuperficial fluid velocity (calculated as: U=4Q/πD², for axial flowfilters, where Q is the fluid flowrate, and D is the diameter of theface area of the filter; and U(R)=Q/2πRX for radial flow filters, whereX is the length of the filter, and R is the radial position betweenR_(i) and R₀), d_(m) is the microorganism diameter (or diameter of anequivalent sphere, if the microorganism is non spherical), k is theBoltzmann's constant (equal to 1.38×10⁻²³ kg·m²/s²·K), T is the fluidtemperature, H is the Hamaker constant (it is typically equal to 10⁻²⁰J), g is the gravitational constant (equal to 9.81 m/s²), ρ_(m) is thedensity of the microorganisms, and ρ_(ƒ) is the fluid density (equal to1 g/mL for water). For the purposes and the materials of the presentinvention, H is equal to 10⁻²⁰ J, T is equal to 298 K, ρ_(m) is equal to1.05 g/mL, μ is equal to 1 mPa·s. Also, for the purposes of the presentinvention, d_(c) is the volume median diameter D_(V,0.5), which is theparticle diameter such that 50% of the total particle volume is inparticles of smaller diameter. Also, the average fluid residence time iscalculated as:

${\tau = \frac{{ɛ\pi}\; D^{2}L}{4Q}},$for axial flow filters, and

${\tau = \frac{{{ɛ\pi}\left( {R_{0}^{2} - R_{i}^{2}} \right)}X}{Q}},$for radial flow filters. (5)

The sticking coefficient, α, is typically calculated experimentally, forexample using the “microbe and radiolabel kinesis” (MARK) techniquedescribed in Gross et al. (Water Res., 29(4), 1151-1158 (1995)). Thesingle-collector efficiency, η, of the filters of the present inventionmay be greater than about 0.002, preferably greater than about 0.02,preferably greater than about 0.2, preferably greater than about 0.4,more preferably greater than about 0.6, and most preferably betweenabout 0.8 and about 1. The filter coefficient, λ, of the filters of thepresent invention may be greater than about 10 m⁻¹, preferably greaterthan about 20 m⁻¹, more preferably greater than about 30 m⁻¹, mostpreferably greater than about 40 m⁻¹, and/or less than about 20,000 m⁻¹,preferably less than about 10,000 m⁻¹, more preferably less than about5,000 m⁻¹, and most preferably less than about 1,000 m⁻¹.

The F-BLR of filters of the present invention containing mesoporous, ormesoporous and basic, or mesoporous, basic, and reduced-oxygen activatedcarbon particles, when measured according to the test procedure setforth herein, may be greater than about 2 logs, preferably greater thanabout 3 logs, more preferably greater than about 4 logs, and mostpreferably greater than about 6 logs. The F-VLR of filters of thepresent invention containing mesoporous, or mesoporous and basic, ormesoporous, basic, and reduced-oxygen activated carbon particles , whenmeasured according to the test procedure set forth herein, may begreater than about 1 log, preferably greater than about 2 logs, morepreferably greater than about 3 logs, and most preferably greater thanabout 4 logs.

In one preferred embodiment of the present invention, the filterparticles comprise mesoporous activated carbon particles that arewood-based activated carbon particles. These particles have a BETspecific surface area between about 1,000 m²/g and about 2,000 m²/g,total pore volume between about 0.8 mL,/g and about 2 mL/g, and sum ofthe mesopore and macropore volumes between about 0.4 mL/g and about 1.5mL/g.

In another preferred embodiment of the present invention, the filterparticles comprise mesoporous and basic activated carbon particles thatare wood-based activated carbon particles. These particles have a BETspecific surface area between about 1,000 m²/g and about 2,000 m²/g,total pore volume between about 0.8 mL/g and about 2 mL/g, and sum ofthe mesopore and macropore volumes between about 0.4 mL/g and about 1.5mL/g.

In yet another preferred embodiment of the present invention, the filterparticles comprise mesoporous, basic, and reduced-oxygen activatedcarbon particles that were initially acidic and rendered basic andreduced-oxygen with treatment in a dissociated ammonia atmosphere. Theseparticles are wood-based activated carbon particles. The treatmenttemperature is between about 925° C. and about 1,000° C., the ammoniaflowrate is between about 1 standard L/h.g and about 20 standard L/h.g,and the treatment time is between about 10 minutes and about 7 hours.These particles have a BET specific surface area between about 800 m²/gand about 2,500 m²/g, total pore volume between about 0.7 mL/g and about2.5 mL/g, and sum of the mesopore and macropore volumes between about0.21 mL/g and about 1.7 mL/g. A non-limiting example of an acidicactivated carbon that is converted to a basic and reduced-oxygenactivated carbon is set forth below.

In even yet another preferred embodiment of the present invention, thefilter particles comprise mesoporous, basic, and reduced-oxygenactivated carbon particles, that were initially mesoporous and basic,with treatment in an inert (i.e., helium) atmosphere. These particlesare wood-based activated carbon particles. The treatment temperature isbetween about 800° C. and about 1,000° C., the helium flowrate isbetween about 1 standard L/h.g and about 20 standard L/h.g, and thetreatment time is between about 10 minutes and about 7 hours. Theseparticles have a BET specific surface area between about 800 m²/g andabout 2,500 m²/g, total pore volume between about 0.7 mL/g and about 2.5mL/g, and sum of the mesopore and macropore volumes between about 0.21mL/g and about 1.7 mL/g. A non-limiting example of a basic activatedcarbon that is converted to a basic and reduced-oxygen activated carbonis set forth below.

III. Silver and Silver Containing Materials

It is known that the presence of metals in active carbon can greatlyenhance the efficiency and selectivity of the active carbon when it isemployed in filtering applications. Specifically, the presence of silvercan improve the microbial removal of carbon based water filters. Andmore specifically, the Bacterial Removal Index (BRI) and the ViralRemoval Index (VRI) can both be increased with the incorporation ofsilver.

Thus, in one preferred aspect, the present invention is directed to afilter for providing potable water. The filter comprises a housinghaving an inlet and an outlet, and a filter material disposed withinsaid housing formed at least in part from a plurality of mesoporousactivated carbon filter particles and particles selected from the groupconsisting of mesoporous activated carbon filter particles coatedentirely with silver or a silver containing material, mesoporousactivated carbon filter particles partially coated with silver or asilver containing material, silver particles and mixtures thereof. Thereis further provided a kit comprising the filter described directlyabove, and a package for containing the filter. Further, either thepackage or the filter housing comprises information that the filter orfilter material provides: bacterial removal; virus removal; microbialremoval; killing of bacteria, killing of viruses, killing of microbials,or any combination of these.

More specifically, the filter material of the present invention cancomprise, among other things, an ad-mixture of silver and mesoporousactivated carbon filter particles, mesoporous activated carbon filterparticles coated partially or entirely with silver and/or a silvercontaining material; mesoporous activated carbon filter particles coatedpartially or entirely with silver or a silver containing material; or anad-mixture of mesoporous activated carbon filter particles, mesoporousactivated carbon filter particles coated partially or entirely withsilver and/or a silver containing material. Preferably, the weight ratioof the silver or silver-containing material to mesoporous activatedcarbon filter particles is from about 1:10,000 to about 1:1, based onthe weight of the silver or silver-containing material, respectively,and having a BET surface area of at least 800 square meters per gram anda bulk density of at least 0.1 gram per cubic centimeter.

Methods for adding silver to a carbon based matrix are known, and any ofthese methods are suitable to produce the filter material of the presentinvention. See for example, U.S. Pat. Nos. 4,482,641 and 4,045,553,issued to Wennerberg, on Nov. 13, 1984, and Mitsumori et al., on Aug.30, 1977, respectively. See also, Dimitry, U.S. Pat. No. 3,886,093,which discloses activated carbons having uniformly distributed activemetal sites and a method for making such activated carbons. The methodof Dimitry involves mixing an aqueous solution of a lignin salt with anaqueous solution of a transition metal salt to precipitate thetransition metal and lignin as a metal lignate. The transition metalmust be capable of forming a chemical bond with the lignin and in sodoing precipitating the lignin from solution as a metal lignate. Dimitrydiscloses that the time required to complete the precipitation is lessthan one hour and that usually 30 minutes is sufficient for thispurpose. According to Dimitry, suitably the wet metal lignateprecipitate can then be dried in a spray drier. The precipitate is thencarbonized at a temperature between 371° C. and 983° C. and finallyactivated at a temperature between 760° C. and 1065° C. Dimitry statesthat, although drying the metal lignate precipitate is not critical toform an activated carbon product, drying is necessary to form a highsurface area end product. The Dimitry, Mitsumori et al. and Wennerbergpatents are incorporated herein in their entirety by reference.

While not intending to limit the present invention, one method ofproducing a substantially uniform dispersion of a silver orsilver-containing material on a porous carbon matrix comprises: forminga uniform co-crystallite of a precursor of the silver orsilver-containing material and of a carbon precursor as defined above;forming a uniform powdered mixture of the co-crystallite and organicsolids comprising an alkali metal hydroxide; pyrolizing the powderedmixture in an inert atmosphere at a temperature in the range of fromabout 400° C. to about 980° C. to form the carbon matrix having thesilver or silver-containing material substantially uniformly dispersedtherein; and separating unreacted inorganic material and inorganicreaction products other than the dispersed silver or silver-containingmaterial from the porous carbon matrix.

Any of a variety of known techniques can be employed to form theco-crystallite in the method of this invention which affords uniformco-crystallization, that is, simultaneous crystallization, of the carbonprecursor and the precursor of the silver or silver-containing materialand the formation of a substantially uniform co-crystallite thereof.Homogeneity of the co-crystallite mixture is essential to the ultimateformation of a uniform dispersion of the silver or silver-containingmaterial in high surface area active carbon. A preferred technique toform the uniform co-crystallite of the carbon precursor and precursor ofthe silver or silver-containing material in the method of this inventioninvolves the formation of a stable solution of both such precursors in asuitable solvent and spray drying such solution to dryness. In suchtechnique, solvent removal must be carried out rapidly enough tomaximize rapid, simultaneous and homogeneous co-crystallization of bothprecursors from solution. Spray drying provides the desired rapidevaporation to insure rapid, simultaneous and uniform co-crystallizationand formation of a homogeneous co-crystallite of both precursors.

In a spray drying system which is suitable for use in carrying out thespray drying step to produce the filter material of this invention, asolution of the carbon precursor and of the precursor of the silver orsilver-containing material is introduced into a drying chamber through anozzle. A hot inert gas such as nitrogen is introduced into the dryingchamber through a line which surrounds the nozzle and serves to assistin atomizing the solution entering the drying chamber through thenozzle, to accelerate and raise the temperature of the atomized solutiondroplets and thereby to promote substantially instantaneous evaporationof solvent therefrom to afford a homogeneous co-crystallite powder. Airis introduced into the drying chamber to sweep the co-crystallite powderand nitrogen downward in the drying chamber where the bulk of theco-crystallite powder falls to the bottom of the drying chamber, whereit collects and from which it is later removed for use in the subsequentsteps of the method of this invention. Gas passes from the dryingchamber and then to a cyclone system where co-crystallite powderentrained in the gas stream is separated from the gas and passesdownward through a line for collection. The weight ratio of thedispersed metal or metal-containing material-to-the active carbon matrixin the composition of this invention is preferably from 1:10,000 to 1:1,based on the weight of the metal or metal-containing material,respectively.

IV. Treatment Examples

EXAMPLE 1 Treatment of a Mesoporous and Acidic Activated Carbon ToProduce a Mesoporous, Basic, and Reduced-Oxygen Activated Carbon

About 2 kg of the CARBOCHEM® CA-10 mesoporous and acidic wood-basedactivated carbon particles from Carbochem, Inc., of Ardmore, Pa., areplaced on the belt of a furnace Model BAC-M manufactured by C.I. Hayes,Inc., of Cranston, R.I. The furnace temperature is set to about 950° C.,the treatment time is about 4 hours, and the atmosphere is dissociatedammonia flowing with a volumetric flowrate of about 12,800 standard L/h(i.e., about 450 standard ft³/h, or equivalently, about 6.4 standardL/h.g). The treated activated carbon particles are called TA4-CA-10, andtheir BET isotherm, mesopore volume distribution, and point of zerocharge analyses are illustrated in FIGS. 1 a, 2 a, and 3 a,respectively. Numerical values for BET, the sum of mesopore andmacropore volumes, point of zero charge, BRI/BLRI, VRI/VLRI, bulk oxygenpercentage by weight, and ORP are shown in Section VII.

EXAMPLE 2 Treatment of a Mesoporous and Basic Activated Carbon toProduce a Mesoporous, Basic, and Reduced-oxygen Activated Carbon

About 2 kg of the MeadWestvaco Nuchar® RGC mesoporous and basicwood-based activated carbon particles from MeadWestvaco Corp., ofCovington, Va., are placed on the belt of a furnace Model BAC-Mmanufactured by C.I. Hayes, Inc., of Cranston, R.I. The furnacetemperature is set to about 800° C., the treatment time is 4. hours, andthe atmosphere is helium flowing with a volumetric flowrate of about12,800 standard L/h (i.e., about 450 standard ft³/h, or equivalently,about 6.4 standard L/h.g). The treated activated carbon particles arecalled THe4-RGC, and their BET isotherm, mesopore volume distribution,and point of zero charge analyses are illustrated in FIGS. 1 b, 2 b, and3 b, respectively. Numerical values for BET, the sum of mesopore andmacropore volumes, point of zero charge, BRI/BLRI, VRI/VLRI, bulk oxygenpercentage by weight, and ORP are shown in Section VII.

V. Filters of the Present Invention

Referring to FIG. 4, an exemplary filter made in accordance with thepresent invention will now be described. The filter 20 comprises ahousing 22 in the form of a cylinder having an inlet 24 and an outlet26. The housing 22 can be provided in a variety of forms, shapes, sizes,and arrangements depending upon the intended use and desired performanceof the filter 20, as known in the art. For example, the filter 20 can bean axial flow filter, wherein the inlet 24 and outlet 26 are disposed sothat the liquid flows along the axis of the housing 22. Alternatively,the filter 20 can be a radial flow filter wherein the inlet 24 andoutlet 26 are arranged so that the fluid (e.g., either a liquid, gas, ormixture thereof) flows along a radial of the housing 22. Either in axialor radial flow configuration, filter 20 may be preferably configured toaccommodate a face area of at least about 0.5 in.² (3.2 cm²), morepreferably at least about 3 in.² (19.4 cm²), and most preferably atleast about 5 in.² (32.2 cm²), and preferably a filter depth of at leastabout 0.125 in. (0.32 cm) of at least about 0.25 in. (0.64 cm), morepreferably at least about 0.5 in. (1.27 cm), and most preferably atleast about 1.5 in. (3.81 cm). For radial flow filters, the filterlength may be at least 0.25 in. (0.64 cm), more preferably at leastabout 0.5 in. (1.27 cm), and most preferably at least about 1.5 in.(3.81 cm). Still further, the filter 20 can include both axial andradial flow sections.

The housing may also be formed as part of another structure withoutdeparting from the scope of the present invention. While the filters ofthe present invention are particularly suited for use with water, itwill be appreciated that other fluids (e.g., air, gas, and mixtures ofair and liquids) can be used. Thus, the filter 20 is intended torepresent a generic liquid filter or gas filter. The size, shape,spacing, alignment, and positioning of the inlet 24 and outlet 26 can beselected, as known in the art, to accommodate the flow rate and intendeduse of the filter 20. Preferably, the filter 20 is configured for use inresidential or commercial potable water applications, including, but notlimited to, whole house filters, refrigerator filters, portable waterunits (e.g., camping gear, such as water bottles), faucet-mount filters,under-sink filters, medical device filters, industrial filters, airfilters, etc. Examples of filter configurations, potable water devices,consumer appliances, and other water filtration devices suitable for usewith the present invention are disclosed in U.S. Pat. Nos. 5,527,451,5,536,394, 5,709,794, 5,882,507, 6,103,114, 4,969,996, 5,431,813,6,214,224, 5,957,034, 6,145,670, 6,120,685, and 6,241,899, thesubstances of which are incorporated herein by reference. For potablewater applications, the filter 20 may be preferably configured toaccommodate a flow rate of less than about 8 L/min, or less than about 6L/min, or between about 2 L/min and about 4 L/min, and the filter maycontain less than about 2 kg of filter material, or less than about 1 kgof filter material, or less than about 0.5 kg of filter material.Further, for potable water applications, the filter 20 may be preferablyconfigured to accommodate an average fluid residence time of at leastabout 3 s, preferably at least about 5 s, preferably at least about 7 s,more preferably at least about 10 s, and most preferably at least about15 s. Still further, for potable water applications, the filter 20 maybe preferably configured to accommodate a filter material pore volume ofat least about 0.4 cm³, preferably at least about 4 cm³, more preferablyat least about 14 cm³, and most preferably at least about 25 cm³.

The filter 20 also comprises a filter material 28 which may be used incombination with other filter systems including reverse osmosis systems,ultra-violet light systems, ionic exchange systems, electrolyzed watersystems, and other water treatment systems known to those with skill inthe art.

The filter 20 also comprises a filter material 28, wherein the filtermaterial 28 includes one or more filter particles (e.g., fibers,granules, etc.). One or more of the filter particles can be mesoporous,more preferably mesoporous and basic, and most preferably mesoporous,basic and reduced oxygen and possess the characteristics previouslydiscussed. The mesoporous; or mesoporous and basic; or mesoporous, basicand reduced oxygen activated carbon filter material 28 can be coatedeither partially or in its entirety with silver, a silver containingmaterial, or combinations thereof. The mesoporous; or nesoporotis andbasic; or mesoporous, basic and reduced oxygen activated carbon filtermaterial 28 can be combined with other materials selected from the groupconsisting of activated carbon powders, activated carbon granules,activated carbon fibers, zeolites, activatied alumina, activatedmagnesia, diatomaceous earth, silver particles, activated silica,hydrotalcites, glass, polyethylene fibers, polypropylene fibers,ethylene maleic anhydride copolymers fibers, sand, clay and mixturesthereof. The other materials can be coated either partially or in theirentirety with silver, a silver containing material, or combinationsthereof. Examples of filter materials and combinations of filtermaterials that mesoporous and basic activated carbon may be combinedwith are disclosed in U.S. Pat. Nos. 6,274,041, 5,679,248, which areherein incorporated by reference, and U.S. patent application Ser. No.09/628,632, which is herein incorporated by reference. As previouslydiscussed, the filter material can be provided in either a loose orinterconnected form (e.g., partially or wholly bonded by a polymericbinder or other means to form an integral structure).

The filter material may be used for different applications (e.g., use asa pre-filter or post-filter) by varying the size, shape, complexformations, charge, porosity, surface structure, functional groups, etc.of the filter particles as discussed above. The filter material may alsobe mixed with other materials, as just described, to suit it for aparticular use. Regardless of whether the filter material is mixed withother materials, it may be used as a loose bed, a block (including aco-extruded block as described in U.S. Pat. No. 5,679,248, which isherein incorporated by reference), and mixtures thereof. Preferredmethods that might be used with the filter material include forming ablock filter made by ceramic-carbon mix (wherein the binding comes fromthe firing of the ceramic), using powder between non-wovens as describedin U.S. Pat. No. 6,077,588, which is herein incorporated by reference,using the green strength method as described in U.S. Pat. No. 5,928,588,which is herein incorporated by reference, activating the resin binderthat forms the block, which is herein incorporated by reference, or byusing a resistive heating method as described in PCT Application SerialNo. WO 98/43796.

VI. Filter Examples

EXAMPLE 3 Filter Containing Mesoporous and Basic Activated CarbonParticles

About 18.3 g of Nuchar® RGC mesoporous and basic activated carbon powder(with D_(V,0.5) equal to about 45 μm) from MeadWestvaco Corp. ofCovington, Va., is mixed with about 7 g of Microthene® low-densitypolyethylene (LDPE) FN510-00 binder of Equistar Chemicals, Inc. ofCincinnati, Ohio, and about 2 g of Alusil® 70 aluminosilicate powderfrom Selecto, Inc., of Norcross, Ga. The mixed powders are then pouredinto a circular aluminum mold with about 3 in. (about 7.62 cm) internaldiameter and about 0.5 in. (about 1.27 cm) depth. The mold is closed andplaced in a heated press with platens kept at about 204° C. for 1 h.Then, the mold is allowed to cool to room temperature, opened, and theaxial flow filter is removed. The characteristics of the filter are:face area: about 45.6 cm²; filter depth: about 1.27 cm; filter totalvolume: about 58 mL; filter porosity (for pores greater than about 0.1μm): about 0.43; and filter material pore volume (for pores greater thanabout 0.1 μm): about 25 mL (as measured by mercury porosimetry). Thefilter is placed in the Teflon® housing described in the test proceduresbelow. When the flow rate is about 200 mL/min, the pressure drop of thisfilter is about 17 psi (about 1.2 bar, 0.12 MPa) for about the first2,000 filter pore volumes. Numerical values for F-BLR, F-VLR, η, and αare shown in Section VII.

EXAMPLE 4 Filter Containing Microporous and Basic Activated CarbonParticles

About 26.2 g of coconut microporous and basic activated carbon powder(with D_(V,0.5) equal to about 92 μm) is mixed with 7 g of Microthene®low-density polyethylene (LDPE) FN510-00 binder of Equistar Chemicals,Inc. of Cincinnati, Ohio, and about 2 g of Alusil® 70 aluminosilicatepowder from Selecto, Inc., of Norcross, Ga. The mixed powders are thenpoured into a circular aluminum mold with about 3 in. (about 7.62 cm)internal diameter and about 0.5 in. (about 1.27 cm) depth. The mold isclosed and placed in a heated press with platens kept at about 204° C.for 1 h. Then, the mold is allowed to cool to room temperature, isopened, and the axial flow filter is removed. The characteristics of thefilter are: face area: about 45.6 cm²; filter depth: about 1.27 cm;filter total volume: about 58 mL; filter porosity (for pores greaterthan about. 0.1 μm): about 0.44; and filter material pore volume (forpores greater than about 0.1 μm): about 25.5 mL (as measured by mercuryporosimetry). The filter is placed in the Teflon® housing described inthe test procedures below. When the flow rate is about 200 mL/min, thepressure drop of this filter is about 17 psi (about 1.2 bar, about 0.12MPa) for about the first 2,000 filter pore volumes. Numerical values forF-BLR, F-VLR, η, and α are shown in Section VII.

VII. Test and Calculation Procedures

The following test procedures are used to calculate the BET, point ofzero charge, BRI/BLRI, VRI/VLRI, bulk oxygen percentage by weight, ORP,F-BLR, and F-VLR values discussed herein. Also discussed herein arecalculation procedures for single-collector efficiency, filtercoefficient, average fluid residence time, and F-BLR.

While measurement of the BRI/BLRI and VRI/VLRI values is with respect toan aqueous medium, this is not intended to limit the ultimate use offilter materials of the present invention, but rather the filtermaterials can ultimately be used with other fluids as previouslydiscussed even though the BRI/BLRI and VRI/VLRI values are calculatedwith respect to an aqueous medium. Further, the filter materials chosenbelow to illustrate use of the test procedures are not intended to limitthe scope of the manufacture and/or composition of the filter materialsof the present invention or to limit which filter materials of thepresent invention can be evaluated using the test procedures.

BET Test Procedure

The BET specific surface area and pore volume distribution are measuredusing a nitrogen adsorption technique, such as that described in ASTM D4820-99, the substance of which is herein incorporated by reference, bymultipoint nitrogen adsorption, at about 77K with a Coulter SA3100Series Surface. Area and Pore Size Analyzer manufactured by CoulterCorp., of Miami, Fla. This process can also provide the micropore,mesopore, and macropore volumes. For the TA4-CA-10 filter particles ofExample 1, the BET area is about 1,038 m²/g, micropore volume is about0.43 mL/g, and the sum of the mesopore and macropore volumes is about0.48 mL/g. For the THe4-RGC filter particles of Example 2, the BET areais about 2,031 m²/g, micropore volume is about 0.81 mL/g, and the sum ofthe mesopore and macropore volumes is about 0.68 mL/g. Note that therespective values of the starting materials CA-10 and RGC are: about1,309 m²/g; about 0.54 mL/g; about 0.67 mL/g; and about 1,745 m²/g;about 0.70 mL/g; about 0.61 mL/g, respectively. Typical BET nitrogenisotherm and the mesopore volume distribution for the filter material ofExamples 1 and 2 are illustrated in FIGS. 1 a and 1 b, respectively. Aswill be appreciated, other instrumentation can be substituted for theBET measurements as is known in the art.

Point of Zero Charge Test Procedure

About 0.010 M aqueous KCl solution is prepared from reagent grade KCland water that is freshly distilled under argon gas. The water used forthe distillation is deionized by a sequential reverse osmosis and ionexchange treatment. About 25.0 mL volume of the aqueous KCl solution istransferred into six, about 125 mL flasks, each fitted with a 24/40ground glass stopper. Microliter quantities of standardized aqueous HClor NaOH solutions are added to each flask so that the initial pH rangesbetween about 2 and about 12. The pH of each flask is then recordedusing an Orion model 420A pH meter with an Orion model 9107BN TriodeCombination pH/ATC electrode, manufactured by Thermo Orion Inc., ofBeverly, Mass., and is called “initial pH”. About 0.0750±0.0010 g ofactivated carbon particles are added to each of the six flasks, and theaqueous suspensions are stirred (at about 150 rpm) while stoppered forabout 24 hours at room temperature before recording the “final pH”. FIG.3 a shows the initial and final pH values for the experiments run withCA-10, and TA4-CA-10 activated carbon materials, and FIG. 3 b shows theinitial and final pH values for the experiments run with RGC andThe4-RGC activated carbon materials. The point of zero charge for theCA-10, TA4-CA-10, RGC, and THe4-RGC is about 5.0, about 9.7, about 8.8,and about 8.6, respectively. As will be appreciated, otherinstrumentation can be substituted for this test procedure as is knownin the art.

BRI/BLRI Test Procedure

A PB-900™ Programmable JarTester manufactured by Phipps & Bird, Inc., ofRichmomd, Va., with 2 or more Pyrex® glass beakers (depending on thenumbers of materials tested) is used. The diameter of the beakers isabout 11.4 cm (about 4.5″) and the height is about 15.3 cm (about 6″).Each beaker contains about 500 mL of dechlorinated, municipally-suppliedtap water contaminated with the E. coli microorganisms and a stirrerthat is rotated at about 60 rpm. The stirrers are stainless steelpaddles about 7.6 cm (about 3″) in length, about 2.54 cm (about 1″) inheight, and about 0.24 cm (about 3/32″) in thickness. The stirrers areplaced about 0.5 cm (about 3/16″) from the bottom of the beakers. Thefirst beaker contains no filter material and is used as a control, andthe other beakers contain sufficient quantity of the filter materials,having a Sauter mean diameter less than about 55 μm, so that the totalexternal geometric surface area of the materials in the beakers is about1400 cm². This Sauter mean diameter is achieved by a) sieving sampleswith broad size distribution and higher Sauter mean diameter or b)reducing the size of the filter particles (e.g., if the filter particlesare larger than about 55 μm or if the filter material is in anintegrated or bonded form) by any size-reducing techniques that are wellknown to those skilled in the art. For example, and by no way oflimitation, size-reducing techniques are crushing, grinding, andmilling. Typical equipment that is used for size reduction includes jawcrushers, gyratory crushers, roll crushers, shredders, heavy-duty impactmills, media mills, and fluid-energy mills, such as centrifugal jets,opposed jets or jets with anvils. The size reduction can be used onloose or bonded filter particles. Any biocidal coating on the filterparticles or the filter material should be removed before conductingthis test. Alternatively, uncoated filter particles can be substitutedfor this test.

Duplicate samples of water, each about 5 mL in volume, are collectedfrom each beaker for assay at various times after insertion of thefilter particles in the beakers until equilibrium is achieved in thebeakers that contain the filter particles. Typical sample times are:about 0, about 2, about 4 and about 6 hours. Other equipment can besubstituted as known in the art.

The E. coli bacteria used are the ATCC # 25922 (American Type CultureCollection, Rockville, Md.). The target E. coli concentration in thecontrol beaker is set to be about 3.7×10⁹ CFU/L. The E. coli assay canbe conducted using the membrane filter technique according to process #9222 of the 20^(th) edition of the “Standard Processes for theExamination of Water and Wastewater” published by the American PublicHealth Association (APHA), Washington, D.C., the substance of which isherein incorporated by reference. The limit of detection (LOD) is about1×10³ CFU/L.

Exemplary BRI/BLRI results for the filter materials of Examples 1 and 2are shown in FIG. 5 a and FIG. 5 b. The amount of the CA-10 mesoporousand acidic activated carbon material is about 0.75 g, and that of theTA40-CA-10 mesoporous, basic, and reduced-oxygen activated carbonmaterial is about 0.89 g. The amount of the RGC mesoporous and basicactivated carbon material is about 0.28 g, and that of the THe4-RGCmesoporous, basic, and reduced-oxygen activated carbon material is about0.33 g. All four amounts correspond to about 1,400 cm² external surfacearea. The E. coli concentration in the control beaker in FIG. 5 a isabout 3.7×10⁹ CFU/L, and that in FIG. 5 b is about 3.2×10⁹ CFU/L. The E.coli concentrations in the beakers containing the CA-10, TA4-CA-10, RGC,and THe4-RGC samples reach equilibrium in about 6 hours, and theirvalues are: about 2.1×10⁶ CFU/L, about 1.5×10⁴ CFU/L, about 3.4×10⁶CFU/L, and about 1.2×10⁶ CFU/L, respectively. Then, the respective BRIsare calculated as about 99.94%, about 99.9996%, about 99.91%, and about99.97%, and the respective BLRIs are calculated as about 3.2 log, about5.4 log, about 3.0 log, and about 3.5 log.

VRI/VLRI Test Procedure

The testing equipment and the procedure are the same as in BRI/BLRIprocedure. The first beaker contains no filter material and is used ascontrol, and the other beakers contain a sufficient quantity of thefilter materials, having a Sauter mean diameter less than about 55 μm,so that there is a total external geometric surface area of about 1400cm² in the beakers. Any biocidal coating on the filter particles or thefilter material should be removed before conducting this test.Alternatively, uncoated filter particles or filter material can besubstituted for this test.

The MS-2 bacteriophages used are the ATCC # 15597B from the AmericanType Culture Collection of Rockville, Md. The target MS-2 concentrationin the control beaker is set to be about 2.07×10⁹ PFU/L. The MS-2 can beassayed according to the procedure by C. J. Hurst, Appl. Environ.Microbiol., 60(9), 3462(1994), the substance of which is hereinincorporated by reference. Other assays known in the art can besubstituted. The limit of detection (LOD) is about 1×10³ PFU/L.

Exemplary VRI/VLRI results for the filter materials of Examples 1 and 2are shown in FIG. 6 a and FIG. 6 b. The amount of the CA-10 mesoporousand acidic activated carbon material is about 0.75 g, and that of theTA40-CA-10 mesoporous, basic, and reduced-oxygen activated carbonmaterial is about 0.89 g. The amount of the RGC mesoporous and basicactivated carbon material is about 0.28 g, and that of the THe4-RGCmesoporous, basic, and reduced-oxygen activated carbon material is about0.33 g. All four amounts correspond to about 1,400 cm² external surfacearea. The MS-2 concentration in the control beaker in FIG. 6 a is about6.7×10⁷ PFU/L, and that in FIG. 6 b is about 8.0×10⁷ PFU/L. The MS-2concentrations in the beakers containing the CA-10, TA4-CA-10, RGC, andTHe4-RGC samples reach equilibrium in 6 hours, and their values areabout 4.1×10⁴ PFU/L, about 1×10³ PFU/L, about 3×10³ PFU/L, and less thanabout 1.0×10³ PFU/L (limit of detection), respectively. Then, therespective VRIs are calculated as about 99.94%, about 99.999%, about99.996%, and >about 99.999%, and the respective VLRIs are calculated asabout 3.2 log, about 5 log, about 4.4 log, and >about 5 log.

Bulk Oxygen Percentage by Weight Test Procedure

The-bulk oxygen percentage by weight is measured using the PerkinElmerModel 240 Elemental Analyzer (Oxygen Modification; PerkinElmer, Inc.;Wellesley, Mass.). The technique is based on pyrolysis of the sample ina stream of helium at about 1000° C. over platinized carbon. The carbonsamples are dried overnight in a vacuum oven at about 100° C. As will beappreciated, other instrumentation can be substituted for this testprocedure as is known in the art. Exemplary bulk oxygen percentage byweight values for the filter materials CA-10, TA4-CA-10, RGC andTHe4-RGC are about 8.3%, about 1.1%, about 2.3% and about 0.8%,respectively.

ORP Test Procedure

The ORP is measured using the platinum redox electrode Model 96-78-00from Orion Research, Inc. (Beverly, Mass.), and following the ASTMstandard D 1498-93. The procedure involves the suspension of about 0.2 gof carbon in about 80 mL of tap water, and reading the electrodereading, in mV, after about 5 min of gentle stirring. As will beappreciated, other instrumentation can be substituted for this testprocedure as is known in the art. Exemplary ORP values for the filtermaterials CA-10, TA4-CA-10, RGC and THe4-RGC are about 427 mV, about 285mV, about 317 mV, and about 310 mV, respectively.

F-BLR Test Procedure

The housings for the axial flow filters with mesoporous carbon are madefrom Teflon® and consist of 2 parts, i.e., a lid and a base. Both partshave an outside diameter of about 12.71 cm (about 5″) and insidediameter of about 7.623 cm (about 3″). The lid counter sets in the basewith an o-ring (about 3″ ID and about ⅛″ thickness) compression seal.The inlet and outlet hose barb connectors are threaded into the lid andbase with about 1/16″ NPT pipe threads. About ½″ thick by about 2¾″ ODstainless steel diverter (with about 3/16″ hole on the upstream side andabout 6 mesh screen on the downstream side) is counter set into the lidof the housing. The function of the diverter is to distribute the inletflow over the entire face of the filter. The lid and base of the housingengage such that a compression seal exists sealing the filter within thehousing. The lid and the base held together using four about ¼″fasteners.

The filter is mounted inside the housing and water contaminated withabout 1×10⁸ CFU/L E. coli flows through at a flowrate of about 200mL/min. The total amount of water flowing in can be about 2,000 filtermaterial pore volumes or more. The E. coli bacteria used are the ATCC #25922 (American Type Culture Collection, Rockville, Md.). The E. coliassay can be conducted using the membrane filter technique according toprocess # 9222 of the 20^(th) edition of the “Standard Processes for theExamination of Water and Wastewater” published by the American PublicHealth Association (APHA), Washington, D.C., the substance of which isherein incorporated by reference. Other assays known in the art can besubstituted (e.g. COLILERT®). The limit of detection (LOD) is about1×10² CFU/L when measured by the membrane filter technique, and about 10CFU/L when measured by the COLILERT® technique. Effluent water iscollected after the flow of about the first 2,000 filter material porevolumes, assayed to count the E. coli bacteria present, and the F-BLR iscalculated using the definition.

Exemplary results used to calculate F-BLR are shown in FIG. 7 a for theaxial flow filters of Example 3 and Example 4. The flowrate used in FIG.7 a is about 200 mL/min and the influent concentration of E. coli variedbetween about 1×10⁸ and about 1×10⁹ CFU/L. The filters are challengedwith about 20 L once a week (every Tuesday) and the effluent water isassayed as described above. The average fluid residence time for the RGCfilter is about 7.5 s, and that of the coconut filter is about 7.65 s.The F-BLR of the RGC filter of Example 3 is calculated as about 6.8 log.For the coconut filter of the Example 4 the collection of the effluentwater is stopped at about 40 L (which is equivalent to about 1,570filter material pore volumes) as the filter shows almost completebreakthrough at that volume of water. The F-BLR is calculated as about1.9 log at about 1,570 filter material pore volumes.

F-VLR Test Procedure

The housings for the axial flow filters with mesoporous carbon are thesame as those described in the F-BLR procedure above. Water contaminatedwith about 1×10⁷ PFU/L MS-2 flows through a housing/filter system at aflowrate of about 200 mL/min. The total amount of water flowing in canbe about 2,000 filter material pore volumes or more. The MS-2bacteriophages used are the ATCC # 15597B (American Type CultureCollection, Rockville, Md.). The MS-2 assay can be conducted accordingto the procedure by C. J. Hurst, Appl. Environ. Microbiol., 60(9), 3462(1994), the substance of which is herein incorporated by reference.Other assays known in the art can be substituted. The limit of detection(LOD) is 1×10³ PFU/L. Effluent water is collected after the flow ofabout the first 2,000 filter material pore volumes, assayed to count theMS-2 bacteriophages present, and the F-VLR is calculated using thedefinition.

Exemplary results used to calculate F-VLR are shown in FIG. 7 b for theaxial flow filters of Example 3 and Example 4. The flowrate used in FIG.7 b is about 200 mL/min and the influent concentration of MS-2 variedaround about 1×10⁷ PFU/L. The filters are challenged with about 20 Lonce a week (every Tuesday) and the effluent water is assayed asdescribed above. The F-VLR of the RGC filter of Example 3 is calculatedas >about 4.2 log. For the coconut filter of the Example 4 thecollection of the effluent water is stopped at about 40 L (which isequivalent to about 1,570 filter material pore volumes) as the filtershows almost complete breakthrough at that volume of water. The F-BLR iscalculated as about 0.3 log at about 1,570 filter material pore volumes.

Calculation Procedures for Single-collector Efficiency, FilterCoefficient, Average Fluid Residence Time, and F-BLR

The single-collector efficiency calculation for the filters usesEquation 4 and the dimensionless numbers described after that equation.Exemplary calculations for the axial flow RGC filter of Example 3 usingthe following parameters: ε=0.43, d_(m)=1 μm, d_(c)=45 μm, H=10⁻²⁰ J,ρ_(m)=1.058 g/mL, ρ_(ƒ)=1.0 g/mL, μ=1 mPa·s, T=298 K, water flowrateQ=200 mL/min, filter diameter D=7.623 cm, and U=0.0007 m/s, giveη=0.01864. For the same parameters and for α=1, the filter coefficientis calculated according to Equation 2 as: λ=354.2 m⁻¹. Furthermore, theF-BLR of the same filter is calculated according to Equation 3 as about1.95 log. Similar exemplary calculations for the coconut filter ofExample 4, using the same parameters as above, give η=0.00717 and λ=65.5m⁻¹. Finally, the F-BLR of the same filter is calculated according toEquation 3 as about 0.36 log.

The present invention may additionally include information that willcommunicate to the consumer, by words and/or by pictures, that use ofcarbon filter particles and/or filter material of the present inventionwill provide benefits which include removal of microorganisms, and thisinformation may include the claim of superiority over other filterproducts. In a highly desirable variation, the information may includethat use of the invention provides for reduced levels of nano-sizedmicroorganisms. Accordingly, the use of packages in association withinformation that will communicate to the consumer, by words and or bypictures, that use of the invention will provide benefits such aspotable, or more potable water as discussed herein, is important. Theinformation can include, e.g., advertising in all of the usual media, aswell as statements and icons on the package, or the filter itself, toinform the consumer.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference, the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention.

The embodiments described herein were chosen and described to providethe best illustration of the principles of the invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

1. A filter for providing potable water, comprising: (a) a housinghaving an inlet and an outlet; and (b) a filter material disposed withinsaid housing formed at least in part from a plurality of filterparticles consisting of mesoporous activated carbon, wherein at least aportion of said plurality of filter particles is at least partiallycoated with silver or a silver-containing material, and wherein: (i) thesum of the mesopore and macropore volumes of said filter particles isbetween about 0.2 mL/g and about 2 mL/g; wherein mesopore means anintra-particle pore having a diameter between 2 nm and 50 nm andmacropore means an intra-particle pore having a diameter greater than 50nm; (ii) the total pore volume of said filter particles is greater thanabout 0.4 mL/g and less than about 3 mL/g; and (iii) the ratio of thesum of the mesopore and macropore volumes to the total pore volume ofsaid filter particles is greater than about 0.3; wherein said filter isoperable to remove microorganisms from water flowing into said inlet andout of said outlet; and wherein said filter has a Filter Bacteria LogRemoval of greater than about 2 logs and a Filter Viruses Log Removal ofgreater than about 1 log.
 2. The filter of claim 1, wherein the sum ofthe mesopore and the macropore volumes of said plurality of filterparticles is from greater than 0.4 mL/g to about 2 mL/g.
 3. The filterof claim 1, wherein said plurality of filter particles has a BacteriaRemoval Index of greater than about 99% and a Viruses Removal Index ofgreater than about 90%.
 4. The filter of claim 1, wherein said filtermaterial has a single-collector efficiency, η, of between about 0.005and 0.25, and a filter coefficient, λ, between about 4.0 m⁻¹ and about14,000 m⁻¹.
 5. The filter of claim 1, wherein said plurality of filterparticles are basic and have a point of zero charge between about 9 andabout 12, an Oxidation Reduction Potential between about 290 mV andabout 175 mV.
 6. A filter for providing potable water, comprising: (a) ahousing having an inlet and an outlet; and (b) a filter materialdisposed within said housing formed at least in part from a plurality offilter particles consisting of mesoporous activated carbon and othermaterials selected from the group consisting of activated carbonpowders, activated carbon granules, activated carbon fibers, zeolites,activated alumina, activated magnesia, diaromaceous earth, activatedSilica, hydrotalcites, glass, polyethylene fibers, polypropylene fibers,ethylene maleic anhydride copolymers fibers, sand, clay and mixturesthereof, wherein at least a portion of the other materials are coatedwith silver or a silver-containing material, wherein: (i) the sum of themesopore and macropore volumes of said filter particles is between about0.2 mL/g and about 2 mL/g; wherein mesopore means an intra-particle porehaving a diameter between 2 nm and 50 nm, and macropore means anintra-particle pore having a diameter greater than 50 nm; (ii) the totalpore volume of said filter particles is greater than about 0.4 mL/g andless than about 3 mL/g; and (iii) the ratio of the sum of the mesoporeand muacropore volumes to the total pore volume of said filter particlesis greater than about 0.3; wherein said filter is operable to removemicroorganisms from water flowing into said inlet and out of saidoutlet; and wherein said filter has a Filter Bacteria Log Removal ofgreater than about 2 logs and a-Filter Viruses Log Removal of greaterthan about 1 log.
 7. A kit comprising: i) a filter according to claim 1;and ii) a package for containing the filter; wherein either the packageor the filter housing comprises information that the filter or filtermaterial provides: bacterial removal; virus removal; microbial removal;killing of bacteria, killing of viruses, killing of microbials, or anycombination of these.
 8. A kit comprising: i) a filter according toclaim 6; and ii) a package for containing the filter; wherein either thepackage or the filter housing comprises information that the filter orfilter material provides: bacterial removal; virus removal; microbialremoval; killing of bacteria, killing of viruses, killing of microbials,or any combination of these.
 9. A process for providing potable water,comprising passing contaminated water through the filter of claim 1 toprovide potable water.
 10. A process for providing potable water,comprising passing contaminated water through the filter of claim 6 toprovide potable water.
 11. The filter of claim 2, wherein the sum of themesopore and macropore volume of said filter particles is greater thanabout 0.4 mL/g and less than about 1 mL/g.
 12. The filter of claim 1,wherein the total pore volume of said filter particles is greater thanabout 0.4 mL/g and less than about 2 mL/g.
 13. The filter of claim 1,wherein the pore volume is at least 0.03 mL/g for pore diameters betweenabout 4 nm and about 6 nm.
 14. The filter of claim 1, wherein saidfilter has a Filter Bacteria Log Removal of greater than about 4 logs,and a Filter Viruses Log Removal of greater than about 2 logs.
 15. Thefilter of claim 14, wherein said filter has a Filter Bacteria LogRemoval of greater than about 6 logs, and a Filter Viruses Log Removalof greater than about 4 logs.
 16. The filter of claim 1, wherein saidfilter has a single-collector efficiency, η, of greater than about0.002.
 17. The filter of claim 1, wherein said filter particles arewood-based activated carbon particles having a Brunauer, Emmet, andTeller (BET) specific surface area between about 1,000 m²/g and about2,000 m²/g, a total pore volume between about 0.8 mL/g and about 2 mL/g,and the sum of the mesopore and macropore volumes is between about 0.4mL/g and about 1.5 mL/g.